For the 1HZ I would plan on 14 - 18L/100 Km if it's a fully loaded rig (roof rack, 33" tires, bull bar, dual batteries, side steps and brush bars, rear bar with dual swing outs, roller drawers in rear, fridge, water, tools recovery gear, food and camping gear).
What do you mean when you say 4.2 turbo: aftermarket or factory? If factory, what engine variant (1HD-T or 1HD-FTE)?
Cheers,
P